This core supports activities common to all six laboratories which are most efficiently and economically conducted as single operations that require high quality control. The core also supports maintenance of equipment used in the core operations as well as common equipment jointly used by investigators in the six laboratories. We have identified those operations which would ordinarily be done separately in each separate laboratory, using similar procedures and requiring quality control. Consolidation of these into single operations makes each operation more efficient and therefore economical, and in addition, it provides a common standard and saves valuable time and effort for the technical staff of the separate laboratories. Services and operations provided by the core will include: preparation of large pools of commonly used monoclonal antibodies whether obtained from ascitic fluid or mass produced from culture using a mammalian cell culture system (Endotronics Acusyst-R), preparing and testing fluorescent probes used for flow cytometric analyses, transplantation and maintenance of tumors and tumor cell lines, maintenance of breeding records for transgenic and SCID mice,.preparation of media, and dishwashing. An experienced research technician will be responsible for the day to day operations of the core and will supervise the junior laboratory helper who will be responsible for dishwashing and for the more routine tasks.